It has long been recognized that heterophase solids might have unique properties which can be exploited for particular purposes. For example, esoteric metal structures have been developed in which a fiber phase is grown in situ in a continuous phase and the fiber phase consists of a metal carbide or one metal alloy or a metal of a particular crystillographic structure, while the continuous phase is the metal whose carbide forms the fibers, is another metal or a metal alloy, and can be used for high temperature applications in turbines or where high strength and high temperature strength are necessary.
In recent years, attention has turned to MC and MMC materials in which, in general, the filamentary phase has been formed from an accumulation of ceramic fibers which can be filled with the continuous phase, e.g. the metal phase.
In some cases, the ceramic of the filamentary phase is formed by depositing a ceramic coating on metal. Reference may be had, with respect to prior art techniques for depositing ceramic coatings, to the article entitled "Physical Vapor Deposition of Ceramic Coatings for Gas Turbine Engine Components", (by R.E. Demaray et al, ASME ref 82 - GT -264).
Ceramic fibers for rise in composites or otherwise are described in the article entitled "Ceramics at the `Cutting Edge`", by L.M. Sheppard, advanced Materials and Processes Inc. METAL PROGRESS 8/87, pages 73 ff. "Vapor-Phase Synthesis of Ceramics" by L.M. Sheppard, op. cit 4/87 pages 53 ff describes various techniques for producing ceramics from a vapor phase.
"A Composites `Wish List`", by E.J. Kubel, Jr., op. cit 10/87 pages 47 ff describes a variety of needs in the MC and MMC field.
Complex composites are described by Kevin Haynes and Hun Yeh in "Si.sub.3 N.sub.4 Matrix Composite Development" and by T.N. Tiegs: and P.F. Becher in "Alumina-SiC Whisker Composites" and by T.Y. Tien, T.K. Brog and A.K. Li in "Toughened Ceramics in the System Al.sub.2 O.sub.3 :CR.sub.2 O.sub.3 /ZrO.sub.2 :HfO.sub.2 ".
Attention may also be directed to the article by S.Musikant, S. Samanta, P. Architetto, and E. Feingold entitled "Development of Mullite/SiC Whisker Composites for Application in the Ceramic Technology for Advanced Heat Engine Program".
It will be apparent, therefore, that in recent years attention has turned to MC and MMC materials for a variety of purposes, especially where high strength, high resistance to heat and like characteristics are important.
While specifically I can mention applications of such materials to pistons in high temperature engines, turbine components and the like, such materials can be used as structural materials where very high strength and high temperature resistance is desired.